With my only run with my G-Tech so far, I was able to get a 15.00@99mph with a wildly-spinning launch.
http://www.automotiveforums.com/vbulletin/t130547.html
From the G-Tech site:
Why is my G-TECH/Pro consistently 2-3 mph above the track?
"G-TECH/Pro is a very accurate machine, and the trap speed result that you get from the G-TECH/Pro is actually more accurate than the racetrack. Reason is that the racetrack averages your speed over a 60 feet stretch between two beams and G-TECH/Pro measures your speed at the exact 1/4 mile point."
http://www.gtechpro.com/gtechpro_whatcanitdo.html
Yeah, so I'm bragging...so what
?